Method for predicting cervical shortening and preterm birth

ABSTRACT

The present invention provides method for predicting risk of cervical shortening, methods for predicting risk of preterm labour (PTL), and methods for characterising a pregnant subject having a history of previous PTL, mid-trimester loss or cervical cone biopsy as being in need of surveillance and/or intervention to prevent preterm labour, comprising determining the expression level of one or more of the miRNA molecules identified in Table 1 or Table 2 extracted from a biological sample obtained from said subject and comparing to a control value. Biochips and kits for use in carrying out the methods of the invention are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. § 371 national phase application ofInternational Patent Application No. PCT/GB2016/050618, filed on Mar. 7,2016, which claims priority to GB Application No. 1503792.2, filed Mar.6, 2015. These applications are incorporated by reference herein intheir entirety.

SEQUENCE LISTING SUBMISSION VIA EFS-WEB

A computer readable text file, entitled “pctgb2016050618-seql.txt”,created on or about 7 Mar. 2016 with a file size of about 4 kb containsthe sequence listing for this application and is hereby incorporate byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to microRNAs (miRNAs) that are useful inpredicting cervical shortening and preterm birth. The invention providesmethods and kits for predicting risk of cervical shortening, pretermlabour and for identifying pregnant subjects in need of interventions toprevent preterm labour.

BACKGROUND OF THE INVENTION

Of 600,000 UK live births per annum, approximately 8,000 will be atbirth weights below 1500 g, which equates to a gestational age of lessthan 32 weeks. Of these preterm babies, 1600 will die and a further 600will develop cerebral palsy. The impact of disability increasesdramatically when delivery occurs close to the limits of viability ataround 24 weeks. The EPICURE study described how 25% of babies bornbefore 25 weeks who survive to be discharged from hospital developsevere disability, 25% mild disability and less than 50% aredevelopmentally normal at 30 months of age¹. The economic impact ofproviding long-term health and social care for these families istherefore significant.

Preterm labour (PTL) is a syndrome, not a single disease process. Someaetiologies, for example placental abruption, are unpredictable andunpreventable. Maternal and/or fetal ‘stress’ may cause preterm labourby cortisol-mediated effects upon placental CRH. Multiple pregnancycauses preterm delivery both through placental CRH and throughmechanical stretch of the uterus and cervix. But these are, in general,causes of ‘late’ preterm labour with less severe medical and economicsequelae.

In normal pregnancy, the onset of contractions is preceded by severalweeks of cervical change characterised by decreased collagen andincreased water content, identifiable clinically as effacement andshortening or cervical ‘ripening’. Cervical ripening is mediated byprostaglandin and cytokine secretion in the lower pole of the uterus andassociated with an inflammatory cell infiltration. The later onset ofuterine contractions is mediated by up regulation of a group of‘contraction-associated proteins’ (CAPs) such as prostaglandin andoxytocin receptors, and gap junctions whose expression is repressed byprogesterone. Preterm delivery prior to 32 weeks is associated withchorioamnionitis and ascending bacterial infection but recent studieshave shown that most cases of early preterm labour cannot be attributedsolely to ascending infection.

Classical cervical incompetence (secondary to a congenital weakness oracquired following destructive cervical surgery) is a cause of secondtrimester pregnancy loss and early preterm delivery, and it is nowaccepted that cervical competence is a continuum. In women whose cervixis short or weak, the biochemical processes of cervical ripening mayoccur because of stretch in the lower pole of the uterus. This leads tofurther softening and shortening of the cervix and so to a viciouscycle. Bacteria may then gain access to the uterus and therefore thefinal preterm delivery appears to be associated with infection althoughthe initial initiating factors were not infection specific. There is apoor correlation between the inflammatory response, which stimulatespreterm labour, and the number of bacteria present. In some women thereis an exaggerated inflammatory response to trivial numbers of bacteria.This leads similarly to ripening and shortening of the cervix allowingfurther bacteria to gain access to the uterus and ultimately to a formof preterm delivery clinically indistinguishable to that associated witha weakened cervix. It is therefore possible that, if women at risk ofearly preterm labour can be identified, an intervention whicheffectively switches off the biochemical processes leading to cervicalshortening may prevent or delay the onset of preterm labour andtherefore significantly improve neonatal outcome.

Current approaches for the prediction of PTL are limited. PTL can bepredicted in those known to be at increased risk by serial measurementof cervical length (CL) on trans-vaginal ultrasound. Women who have hada previous PTL, mid-trimester loss (MTL) or cervical cone biopsy areeligible for CL screening, though provision in the UK is not universal.

Women with cervical shortening are at increased risk of spontaneouspreterm delivery, but remain asymptomatic until preterm labour isimminent. Early interventions to prolong pregnancy are available, butcan only be delivered if obstetricians are aware that cervicalshortening has occurred. Vaginal ultrasound can be used to diagnosecervical shortening, but is expensive and invasive, and therefore onlyavailable to a limited number of women attending specialist centres.

If the CL is found to be less than 25 mm there are two availableinterventions: cervical cerclage and progesterone treatment. Cerclageacts not only to support a weak cervix, but to retain the anti-bacterialmucous plug and prevent stretch mediated activation of inflammation.Progesterone treatment is effective and probably acts via inhibition ofcontraction associated proteins and nuclear factor kB expression.

However, CL surveillance clinics are labour intensive, expensive and donot provide care and intervention for women without pre-existing riskfactors. In addition, using only past medical history to screen foreligibility lacks sensitivity and >80% of women attending such a servicedo not require any intervention and deliver at term gestations.

It has been suggested that routine measurement of cervical length at 18to 22 weeks, linked to progesterone therapy, should be offered to theentire obstetric population¹² ¹³. However, this would be potentiallycostly.

A panel of biomarkers, routinely measured in all pregnancies, which areable to predict future cervical change or PTL itself would therefore beof great value in more accurately targeting pregnant women forsurveillance and therapy. Only one biomarker is currently available topredict PTL; fetal fibronectin (fFN) in cervical or vaginal fluid. fFNis not useful in the distant prediction of early PTL because it isnormally present in cervical secretions at up to 22 weeks gestation.Amniotic fluid or cervical secretion cytokines levels will also predictPTL but only close to the onset of labour². All pregnant women currentlyundergo blood testing to screen for Rhesus group and viral infections at13 weeks of pregnancy; this is an ideal time to screen for risk of earlyPTL and sufficiently early to allow enrolment in a surveillance programand delivery of an intervention.

Careful regulation of gene expression in the myometrium and fetalmembranes is central to controlling the timing of labour onset. miRNAsare small, single-stranded, 19-25 nucleotide molecules that have emergedas important regulators of gene expression in almost all eukaryotes; athird of the protein encoding human genome is thought to be regulated bymiRNAs. miRNAs are non-coding RNAs and function in a manner similar tosmall-interfering RNA to down-regulate gene expression at thepost-transcriptional level. miRNA biogenesis involves a series of stepsthat lead to gene silencing. Briefly, miRNAs are transcribed in thenucleus as longer primary-miRNAs, which are cleaved to form hair-pinshaped precursor-miRNAs. These precursors are exported from the nucleusand further cleaved to form the mature miRNA which associates with theRNA induced silencing complex to target the 3′-untranslated region ofspecific mRNAs and inhibit their translation to protein. miRNAs arepresent in a cell free state in plasma and remain stable and easilymeasurable. Their potential utility as a biomarker of disease orresponse to treatment has consequently been widely acknowledged³.

miRNAs are expressed in a tissue specific manner and therefore theirdifferential expression, both spatially and over time, is a potentiallyrich area of research. miRNA expression in the chorioamniotic membranes,placenta, umbilical cord and myometrium is currently being investigatedby a number of groups. Cyclo-oxygenase 2 (COX2) (which catalyses thesynthesis of prostaglandin which in turn modulates uterine contractions)is regulated at the post-transcriptional level through changes inspecific miRNAs⁴. In addition, knockout studies of proteins essentialfor miRNA biogenesis have demonstrated that miRNAs play an essentialrole in reproduction. DICER is an RNAse III endonuclease that isessential for the biogenesis of miRNAs and small interfering (si)RNAs,and loss of DICER within ovarian granulosa cells, luteal tissue, oocyte,oviduct and potentially the uterus, renders murine females infertile⁵.In addition, disruption of the gene for Ago 2, another importantcomponent of RNA interference (RNAs) leads to embryo death early afterimplantation⁶. Intriguingly, placental miRNAs are also released into thematernal circulation. They remain stable and are easily detectable inblood and it has therefore been proposed that they might provide novel,non-invasive biomarkers for placental disorders such as preeclampsia orfetal growth restriction⁷.

Current understanding of how miRNA expression may regulate humanmyometrial gene expression and hence contractions, is limited. Renthalet al found that the miR-200 family of miRNAs is up-regulated in thelabouring murine and human myometrium at term⁸. ZEB1 and ZEB2 wereidentified as two targets of this group in functional studies, and werefound to be co-ordinately down-regulated in mouse models of PTL. ZEB1and ZEB2 act as transcriptional repressors, which may inhibit theexpression of contraction associated genes, oxytocin receptor andconnexin-43, and block oxytocin induced contractility in culturedmyometrial cells.

Williams et al linked miR-200a to progesterone metabolism through therepression of STAT5b, a transcriptional repressor of the P4 metabolisingenzyme 20α-hydroxysteroid dehydrogenase, in the mouse and human uterus⁹.It is unclear how this is relevant to humans where labour is notassociated with a reduction in circulating progesterone.

Recently, a study examining the global expression of miRNAs in cervicaltissue from women following vaginal delivery at term or pre-labour LSCS,described 226 miRNAs expressed in the cervix¹⁰. Furthermore, miR-223,miR-34b and miR-34c were found to have increased expression with labour.Montenegro et al. examined miRNA expression in the fetal membranes infour distinct cohorts: term NL & L, and PTL with or without histologicalchorioamnionitis¹⁴. The authors detected 153 and 152 different miRNAs inat least 50% of samples in the term and preterm groups respectively.They found no difference in the term NL and term L groups, but described13 miRNAs with reduced expression with advancing gestational age. Theyalso found miR-223 and miR-338 had increased in expression in PTLmembranes in the presence of inflammation.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention provides a method forpredicting risk of cervical shortening in a pregnant female subject,comprising determining the expression level of one or more of the miRNAmolecules identified in Table 1 or Table 2 extracted from a biologicalsample obtained from said subject and comparing to a control value,wherein a difference in the expression level of the one or more of themiRNA molecules compared to the control value indicates that the subjectis at high or low risk of cervical shortening.

According to a second aspect, the invention provides a method forpredicting risk of preterm labour (PTL) in a pregnant female subject,comprising determining the expression level of one or more miRNAmolecules identified in Table 1 or Table 2 extracted from a biologicalsample obtained from said subject and comparing to a control value,wherein a difference in the expression level of the one or more of themiRNA molecules compared to the control value indicates that the subjectis at high or low risk of PTL.

According to a third aspect, the invention provides a method forcharacterising a pregnant female subject having a history of previousPTL, mid-trimester loss or cervical cone biopsy as being in need ofcervical ultrasound screening, cervical cerclage and/or progesteronetherapy, comprising determining the expression level of one or moremiRNA molecules identified in Table 1 or Table 2 extracted from abiological sample obtained from said subject and comparing to a controlvalue, wherein a difference in the expression level of the one or moreof the miRNA molecules compared to the control value indicates that thesubject is in need of cervical ultrasound screening, cervical cerclageand/or progesterone therapy.

According to a fourth aspect, the invention provides a method forpredicting the timing of the onset of labour in a pregnant subject whois at term (>37 weeks gestation), comprising determining the expressionlevel of one or more miRNA molecules identified in Table 1 or Table 2extracted from a biological sample obtained from said subject andcomparing to a control value, wherein a difference in the expressionlevel of the one or more of the miRNA molecules compared to the controlvalue indicates the timing of the onset of labour.

According to a fifth aspect, the invention provides a solid substratecomprising one or more probes specific for one or more of the miRNAmolecules in Table 1 or Table 2.

A sixth aspect of the invention is directed to the use of a solidsubstrate according to the fourth aspect of the invention in a methodaccording to any of the first, second or third aspects of the invention.

A seventh aspect of the invention provides a kit for predicting risk ofcervical shortening in a pregnant female subject, comprising one or moreprobes specific for one or more of the miRNA molecules in Table 1 orTable 2.

An eighth aspect of the invention provides a kit for predicting risk ofpreterm labour (PTL) in a pregnant female subject, comprising one ormore probes specific for one or more of the miRNA molecules in Table 1or Table 2.

DESCRIPTION OF THE DRAWINGS

FIG. 1 relates to hsa-let-7a-5p as a predictor of cervical shortening.Expression of hsa-let-7a-5p in plasma of women whose cervix shortened to<25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-let-7a-5p to predict cervical shortening at TPA (B) following PCRanalysis (AUC=0.62). Expression of hsa-let-7a-5p in plasma of womenwhose cervix shortened to <25 mm (n=21) compared with those who did notexhibit cervical shortening (n=16), measured using RT PCR at time pointB (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-let-7a-5p to predict cervical shortening at TPB(AUC=0.69) (D). Expression of hsa-let-7a-5p in plasma of women whosecervix shortened to <25 mm (n=17) compared with those who did notexhibit cervical shortening (n=15), measured using RT PCR (E) at timepoint C (19-21⁺⁶ weeks gestation) (TPC). ROC curve showing sensitivityand specificity of hsa-let-7a-5p to predict cervical shortening at TPC(AUC=0.78) (F). Fold change at each time point of hsa-let-7a-5pexpression in plasma of women who exhibited cervical shortening comparedwith expression in women who had normal cervical lengths (G) Fold changeincreases with gestation.

FIG. 2 relates to hsa-miR-374a-5p as a predictor of cervical shortening.Expression of hsa-miR-374a-5p in plasma of women whose cervix shortenedto <25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-miR-374a-5p to predict cervical shortening at TPA (B) followingPCR analysis (AUC=0.81). Expression of hsa-miR-374a-5p in plasma ofwomen whose cervix shortened to <25 mm (n=21) compared with those whodid not exhibit cervical shortening (n=16), measured using RT PCR attime point B (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showingsensitivity and specificity of hsa-miR-374a-5p to predict cervicalshortening at TPB (AUC=0.79) (D). Expression of hsa-miR-374a-5p inplasma of women whose cervix shortened to <25 mm (n=17) compared withthose who did not exhibit cervical shortening (n=15), measured using RTPCR at time point C (19-21⁺⁶ weeks gestation) (TPC) (E). ROC curveshowing sensitivity and specificity of hsa-miR-374a-5p to predictcervical shortening at TPC (AUC=0.78) (F). Fold change ofhsa-miR-374a-5p expression at each time point in plasma of women whoexhibited cervical shortening, compared with expression in women who hada normal cervical length (G).

FIG. 3 relates to hsa-miR-15b-5p as a predictor of cervical shortening.Expression of hsa-miR-15b-5p in plasma of women whose cervix shortenedto <25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-miR-15b-5p to predict cervical shortening at TPA (B) followingPCR analysis (AUC=0.81). Expression of hsa-miR-15b-5p in plasma of womenwhose cervix shortened to <25 mm (n=21) compared with those who did notexhibit cervical shortening (n=16), measured using RT PCR at time pointB (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-15b-5p to predict cervical shortening at TPB(AUC=0.79) (D). Expression of hsa-miR-15b-5p in plasma of women whosecervix shortened to <25 mm (n=17) compared with those who did notexhibit cervical shortening (n=15), measured using RT PCR (E) at timepoint C (19-21⁺⁶ weeks gestation) (TPC). ROC curve showing sensitivityand specificity of hsa-miR-15b-5p to predict cervical shortening at TPC(AUC=0.78) (F). Fold change of hsa-miR-15b-5p expression at each timepoint, in plasma of women who exhibited cervical shortening, comparedwith expression in women who had normal cervical lengths (G). Relativeexpression of hsa-miR-15b-5p increases with advancing gestation.

FIG. 4 relates to hsa-miR-19b-3p as a predictor of cervical shortening.Expression of hsa-miR-19b-3p in plasma of women whose cervix shortenedto <25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-miR-19b-3p to predict cervical shortening at TPA (B) followingPCR analysis (AUC=0.74). Expression of hsa-miR-19b-3p in plasma of womenwhose cervix shortened to <25 mm (n=21) compared with those who did notexhibit cervical shortening (n=16), measured using RT PCR at time pointB (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-19b-3p to predict cervical shortening at TPB(AUC=0.80) (D). Expression of hsa-miR-19b-3p in plasma of women whosecervix shortened to <25 mm (n=17) compared with those who did notexhibit cervical shortening (n=15), measured using RT PCR (E) at timepoint C (19-21⁺⁶ weeks gestation) (TPC). ROC curve showing sensitivityand specificity of hsa-miR-19b-3p to predict cervical shortening at TPC(AUC=0.73) (F). Fold change of hsa-miR-19b-3p expression at each timepoint, in plasma of women who exhibited cervical shortening comparedwith expression in women who had normal cervical lengths (G). Foldchange increases with gestation.

FIG. 5 relates to hsa-miR-23a-3p as a predictor of cervical shortening.Expression of hsa-miR-23a-3p in plasma of women whose cervix shortenedto <25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-miR-23a-3p to predict cervical shortening at TPA (B) followingPCR analysis (AUC=0.65). Expression of hsa-miR-23a-3p in plasma of womenwhose cervix shortened to <25 mm (n=21) compared with those who did notexhibit cervical shortening (n=16), measured using RT PCR at time pointB (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-23a-3p to predict cervical shortening at TPB(AUC=0.75) (D). Expression of hsa-miR-23a-3p in plasma of women whosecervix shortened to <25 mm (n=17) compared with those who did notexhibit cervical shortening (n=15), measured using RT PCR (E) at timepoint C (19-21⁺⁶ weeks gestation) (TPC). ROC curve showing sensitivityand specificity of hsa-miR-23a-3p to predict cervical shortening at TPC(AUC=0.76) (F). Fold change of hsa-miR-23a-3p expression at each timepoint, in plasma of women who exhibited cervical shortening, comparedwith expression in women who had normal cervical lengths (G). Relativeexpression of hsa-miR-23a-3p increases with gestation.

FIG. 6 relates to hsa-miR-93-5p as a predictor of cervical shortening.Expression of hsa-miR-93-5p in plasma of women whose cervix shortened to<25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-miR-93-5p to predict cervical shortening at TPA (B) following PCRanalysis (AUC=0.68). Expression of hsa-miR-93-5p in plasma of womenwhose cervix shortened to <25 mm (n=21) compared with those who did notexhibit cervical shortening (n=16), measured using RT PCR at time pointB (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-93-5p to predict cervical shortening at TPB(AUC=0.78) (D). Expression of hsa-miR-93-5p in plasma of women whosecervix shortened to <25 mm (n=17) compared with those who did notexhibit cervical shortening (n=15), measured using RT PCR (E) at timepoint C (19-21⁺⁶ weeks gestation) (TPC). ROC curve showing sensitivityand specificity of hsa-miR-93-5p to predict cervical shortening at TPC(AUC=0.70) (F). Fold change of hsa-miR-93-5p expression at each timepoint, in plasma of women who exhibited cervical shortening, comparedwith expression in women who had normal cervical lengths (G). Relativeexpression of hsa-miR-93-5p increases with advancing gestation.

FIG. 7 relates to hsa-miR-150-5p as a predictor of cervical shortening.Expression of hsa-miR-150-5p in plasma of women whose cervix shortenedto <25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-miR-150-5p to predict cervical shortening at TPA (B) followingPCR analysis (AUC=0.73). Expression of hsa-miR-150-5p in plasma of womenwhose cervix shortened to <25 mm (n=21) compared with those who did notexhibit cervical shortening (n=16), measured using RT PCR at time pointB (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-150-5p to predict cervical shortening at TPB(AUC=0.79) (D). Expression of hsa-miR-150-5p in plasma of women whosecervix shortened to <25 mm (n=17) compared with those who did notexhibit cervical shortening (n=15), measured using RT PCR (E) at timepoint C (19-21⁺⁶ weeks gestation) (TPC). ROC curve showing sensitivityand specificity of hsa-miR-150-5p to predict cervical shortening at TPC(AUC=0.83) (F). Fold change of hsa-miR-150-5p expression at each timepoint, in plasma of women who exhibited cervical shortening, comparedwith expression in women who had normal cervical lengths (G). Relativeexpression of hsa-miR-150-5p increases with advancing gestation.

FIG. 8 relates to hsa-miR-185-5p as a predictor of cervical shortening.Expression of hsa-miR-185-5p in plasma of women whose cervix shortenedto <25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-miR-185-5p to predict cervical shortening at TPA (B) followingPCR analysis (AUC=0.67). Expression of hsa-miR-185-5p in plasma of womenwhose cervix shortened to <25 mm (n=21) compared with those who did notexhibit cervical shortening (n=16), measured using RT PCR at time pointB (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-185-5p to predict cervical shortening at TPB(AUC=0.79) (D). Expression of hsa-miR-185-5p in plasma of women whosecervix shortened to <25 mm (n=17) compared with those who did notexhibit cervical shortening (n=15), measured using RT PCR (E) at timepoint C (19-21⁺⁶ weeks gestation) (TPC). ROC curve showing sensitivityand specificity of hsa-miR-185-5p to predict cervical shortening at TPC(AUC=0.83) (F). Fold change of hsa-miR-185-5p expression at each timepoint, in plasma of women who exhibited cervical shortening, comparedwith expression in women who had normal cervical lengths (G). Theincreased relative expression of hsa-miR-185-5p does not alter withadvancing gestation.

FIG. 9 relates to hsa-miR-191-5p as a predictor of cervical shortening.Expression of hsa-miR-191-5p in plasma of women whose cervix shortenedto <25 mm (n=18) compared with those who did not exhibit cervicalshortening (n=15), measured via real time polymerase chain reaction (RTPCR) at time point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiveroperated characteristic (ROC) curve showing sensitivity and specificityof hsa-miR-191-5p to predict cervical shortening at TPA (B) followingPCR analysis (AUC=0.60). Expression of hsa-miR-191-5p in plasma of womenwhose cervix shortened to <25 mm (n=21) compared with those who did notexhibit cervical shortening (n=16), measured using RT PCR at time pointB (15-17⁺⁶ weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-191-5p to predict cervical shortening at TPB(AUC=0.67) (D). Expression of hsa-miR-191-5p in plasma of women whosecervix shortened to <25 mm (n=17) compared with those who did notexhibit cervical shortening (n=15), measured using RT PCR (E) at timepoint C (19-21⁺⁶ weeks gestation) (TPC). ROC curve showing sensitivityand specificity of hsa-miR-191-5p to predict cervical shortening at TPC(AUC=0.73) (F). Fold change of hsa-miR-191-5p expression at each timepoint, in plasma of women who exhibited cervical shortening, comparedwith expression in women who had normal cervical lengths (G). Relativeexpression of hsa-miR-191-5p increases with advancing gestation.

FIG. 10 relates to hsa-let-7a-5p as a predictor of preterm birth.Expression of hsa-let-7a-5p in plasma of women who delivered prior to 34weeks gestation (n=8) compared with those who delivered at term (n=25),measured via real time polymerase chain reaction (RT PCR) at time pointA (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operated characteristic(ROC) curve showing sensitivity and specificity of hsa-let-7a-5p topredict preterm birth at TPA following PCR analysis (AUC=0.52) (B).Expression of hsa-let-7a-5p in plasma of women who delivered prior to 34weeks gestation (n=10) compared with those who delivered at term (n=27),measured using RT PCR at time point B (15-17⁺⁶ weeks gestation) (TPB)(C). ROC curve showing sensitivity and specificity of hsa-let-7a-5p topredict preterm birth at TPB (AUC=0.64) (D). Expression of hsa-let-7a-5pin plasma of women who delivered prior to 34 weeks gestation (n=7)compared with those who delivered at term (n=25), measured using RT PCRat time point C (19-21⁺⁶ weeks gestation) (TPC) (E). ROC curve showingsensitivity and specificity of hsa-let-7a-5p to predict preterm birth atTPC (AUC=0.0.78) (F). Fold change of hsa-let-7a-5p expression at eachtime point, in plasma of women who delivered prior to 34 weeksgestation, compared with expression in women who delivered at term (G).Relative expression of hsa-let-7a-5p increases at TPC.

FIG. 11 relates to hsa-miR-374a-5p as a predictor of preterm birth.Expression of hsa-miR-374a-5p in plasma of women who delivered prior to34 weeks gestation (n=8) compared with those who delivered at term(n=25), measured via real time polymerase chain reaction (RT PCR) attime point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operatedcharacteristic (ROC) curve showing sensitivity and specificity ofhsa-miR-374a-5p to predict preterm birth at TPA following PCR analysis(AUC=0.68) (B). Expression of hsa-miR-374a-5p in plasma of women whodelivered prior to 34 weeks gestation (n=10) compared with those whodelivered at term (n=27), measured using RT PCR at time point B (15-17⁺⁶weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-374a-5p to predict preterm birth at TPB(AUC=0.69) (D). Expression of hsa-miR-374a-5p in plasma of women whodelivered prior to 34 weeks gestation (n=7) compared with those whodelivered at term (n=25), measured using RT PCR at time point C (19-21⁺⁶weeks gestation) (TPC) (E). ROC curve showing sensitivity andspecificity of hsa-miR-374a-5p to predict preterm birth at TPC(AUC=0.0.72) (F). Fold change of hsa-miR-374a-5p expression at each timepoint, in plasma of women who delivered prior to 34 weeks gestation,compared with expression in women who delivered at term (G). Relativeexpression of hsa-miR-374a-5p increases at TPC.

FIG. 12 relates to hsa-miR-15b-5p as a predictor of preterm birth.Expression of hsa-miR-15b-5p in plasma of women who delivered prior to34 weeks gestation (n=8) compared with those who delivered at term(n=25), measured via real time polymerase chain reaction (RT PCR) attime point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operatedcharacteristic (ROC) curve showing sensitivity and specificity ofhsa-miR-15b-5p to predict preterm birth at TPA following PCR analysis(AUC=0.59) (B). Expression of hsa-miR-15b-5p in plasma of women whodelivered prior to 34 weeks gestation (n=10) compared with those whodelivered at term (n=27), measured using RT PCR at time point B (15-17⁺⁶weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-15b-5p to predict preterm birth at TPB (AUC=0.64)(D). Expression of hsa-miR-15b-5p in plasma of women who delivered priorto 34 weeks gestation (n=7) compared with those who delivered at term(n=25), measured using RT PCR at time point C (19-21⁺⁶ weeks gestation)(TPC) (E). ROC curve showing sensitivity and specificity ofhsa-miR-15b-5p to predict preterm birth at TPC (AUC=0.0.77) (F). Foldchange of hsa-miR-15b-5p expression at each time point, in plasma ofwomen who delivered prior to 34 weeks gestation, compared withexpression in women who delivered at term (G). Relative expression ofhsa-miR-15b-5p is greatest at TPA and TPC.

FIG. 13 relates to hsa-miR-19b-5p as a predictor of preterm birth.Expression of hsa-miR-19b-5p in plasma of women who delivered prior to34 weeks gestation (n=8) compared with those who delivered at term(n=25), measured via real time polymerase chain reaction (RT PCR) attime point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operatedcharacteristic (ROC) curve showing sensitivity and specificity ofhsa-miR-19b-5p to predict preterm birth at TPA following PCR analysis(AUC=0.62) (B). Expression of hsa-miR-19b-5p in plasma of women whodelivered prior to 34 weeks gestation (n=10) compared with those whodelivered at term (n=27), measured using RT PCR at time point B (15-17⁺⁶weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-19b-5p to predict preterm birth at TPB (AUC=0.68)(D). Expression of hsa-miR-19b-5p in plasma of women who delivered priorto 34 weeks gestation (n=7) compared with those who delivered at term(n=25), measured using RT PCR at time point C (19-21⁺⁶ weeks gestation)(TPC) (E). ROC curve showing sensitivity and specificity ofhsa-miR-19b-5p to predict preterm birth at TPC (AUC=0.0.67) (F). Foldchange of hsa-miR-19b-5p expression at each time point, in plasma ofwomen who delivered prior to 34 weeks gestation, compared withexpression in women who delivered at term (G). Relative expression ofhsa-miR-19b-5p is greatest at TPA and TPC.

FIG. 14 relates to hsa-miR-23a-3p as a predictor of preterm birth.Expression of hsa-miR-23a-3p in plasma of women who delivered prior to34 weeks gestation (n=8) compared with those who delivered at term(n=25), measured via real time polymerase chain reaction (RT PCR) attime point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operatedcharacteristic (ROC) curve showing sensitivity and specificity ofhsa-miR-23a-3p to predict preterm birth at TPA following PCR analysis(AUC=0.61) (B). Expression of hsa-miR-23a-3p in plasma of women whodelivered prior to 34 weeks gestation (n=10) compared with those whodelivered at term (n=27), measured using RT PCR at time point B (15-17⁺⁶weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-23a-3p to predict preterm birth at TPB (AUC=0.81)(D). Expression of hsa-miR-23a-3p in plasma of women who delivered priorto 34 weeks gestation (n=7) compared with those who delivered at term(n=25), measured using RT PCR at time point C (19-21⁺⁶ weeks gestation)(TPC) (E). ROC curve showing sensitivity and specificity ofhsa-miR-23a-3p to predict preterm birth at TPC (AUC=0.70) (F). Foldchange of hsa-miR-23a-3p expression at each time point, in plasma ofwomen who delivered prior to 34 weeks gestation, compared withexpression in women who delivered at term (G). Relative expression ofhsa-miR-23a-3p increases with advancing gestation.

FIG. 15 relates to hsa-miR-93-5p as a predictor of preterm birth.Expression of hsa-miR-93-5p in plasma of women who delivered prior to 34weeks gestation (n=8) compared with those who delivered at term (n=25),measured via real time polymerase chain reaction (RT PCR) at time pointA (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operated characteristic(ROC) curve showing sensitivity and specificity of hsa-miR-93-5p topredict preterm birth at TPA following PCR analysis (AUC=0.51) (B).Expression of hsa-miR-93-5p in plasma of women who delivered prior to 34weeks gestation (n=10) compared with those who delivered at term (n=27),measured using RT PCR at time point B (15-17⁺⁶ weeks gestation) (TPB)(C). ROC curve showing sensitivity and specificity of hsa-miR-93-5p topredict preterm birth at TPB (AUC=0.58) (D). Expression of hsa-miR-93-5pin plasma of women who delivered prior to 34 weeks gestation (n=7)compared with those who delivered at term (n=25), measured using RT PCRat time point C (19-21⁺⁶ weeks gestation) (TPC) (E). ROC curve showingsensitivity and specificity of hsa-miR-93-5p to predict preterm birth atTPC (AUC=0.70) (F). Fold change of hsa-miR-93-5p expression at each timepoint, in plasma of women who delivered prior to 34 weeks gestation,compared with expression in women who delivered at term (G). Relativeexpression of hsa-miR-93-5p is greatest at TPC.

FIG. 16 relates to hsa-miR-150-5p as a predictor of preterm birth.Expression of hsa-miR-150-5p in plasma of women who delivered prior to34 weeks gestation (n=8) compared with those who delivered at term(n=25), measured via real time polymerase chain reaction (RT PCR) attime point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operatedcharacteristic (ROC) curve showing sensitivity and specificity ofhsa-miR-150-5p to predict preterm birth at TPA following PCR analysis(AUC=0.59) (B). Expression of hsa-miR-150-5p in plasma of women whodelivered prior to 34 weeks gestation (n=10) compared with those whodelivered at term (n=27), measured using RT PCR at time point B (15-17⁺⁶weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-150-5p to predict preterm birth at TPB (AUC=0.67)(D). Expression of hsa-miR-150-5p in plasma of women who delivered priorto 34 weeks gestation (n=7) compared with those who delivered at term(n=25), measured using RT PCR at time point C (19-21⁺⁶ weeks gestation)(TPC) (E). ROC curve showing sensitivity and specificity ofhsa-miR-150-5p to predict preterm birth at TPC (AUC=0.82) (F). Foldchange of hsa-miR-150-5p expression at each time point, in plasma ofwomen who delivered prior to 34 weeks gestation, compared withexpression in women who delivered at term (G). Relative expression ofhsa-miR-150-5p increases with advancing gestation.

FIG. 17 relates to hsa-miR-185-5p as a predictor of preterm birth.Expression of hsa-miR-185-5p in plasma of women who delivered prior to34 weeks gestation (n=8) compared with those who delivered at term(n=25), measured via real time polymerase chain reaction (RT PCR) attime point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operatedcharacteristic (ROC) curve showing sensitivity and specificity ofhsa-miR-185-5p to predict preterm birth at TPA following PCR analysis(AUC=0.60) (B). Expression of hsa-miR-185-5p in plasma of women whodelivered prior to 34 weeks gestation (n=10) compared with those whodelivered at term (n=27), measured using RT PCR at time point B (15-17⁺⁶weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-185-5p to predict preterm birth at TPB (AUC=0.59)(D). Expression of hsa-miR-185-5p in plasma of women who delivered priorto 34 weeks gestation (n=7) compared with those who delivered at term(n=25), measured using RT PCR at time point C (19-21⁺⁶ weeks gestation)(TPC) (E). ROC curve showing sensitivity and specificity ofhsa-miR-185-5p to predict preterm birth at TPC (AUC=0.73) (F). Foldchange of hsa-miR-185-5p expression at each time point, in plasma ofwomen who delivered prior to 34 weeks gestation, compared withexpression in women who delivered at term (G). Relative expression ofhsa-miR-185-5p is greatest at TPC.

FIG. 18 relates to hsa-miR-191-5p as a predictor of preterm birth.Expression of hsa-miR-191-5p in plasma of women who delivered prior to34 weeks gestation (n=8) compared with those who delivered at term(n=25), measured via real time polymerase chain reaction (RT PCR) attime point A (12-14⁺⁶ weeks gestation) (TPA) (A). Receiver operatedcharacteristic (ROC) curve showing sensitivity and specificity ofhsa-miR-191-5p to predict preterm birth at TPA following PCR analysis(AUC=0.59) (B). Expression of hsa-miR-191-5p in plasma of women whodelivered prior to 34 weeks gestation (n=10) compared with those whodelivered at term (n=27), measured using RT PCR at time point B (15-17⁺⁶weeks gestation) (TPB) (C). ROC curve showing sensitivity andspecificity of hsa-miR-191-5p to predict preterm birth at TPB (AUC=0.66)(D). Expression of hsa-miR-191-5p in plasma of women who delivered priorto 34 weeks gestation (n=7) compared with those who delivered at term(n=25), measured using RT PCR at time point C (19-21⁺⁶ weeks gestation)(TPC) (E). ROC curve showing sensitivity and specificity ofhsa-miR-191-5p to predict preterm birth at TPC (AUC=0.67) (F). Foldchange of hsa-miR-185-5p expression at each time point, in plasma ofwomen who delivered prior to 34 weeks gestation, compared withexpression in women who delivered at term (G). Relative expression ofhsa-miR-185-5p is higher at all three time points, in women who go on todeliver preterm.

FIG. 19 shows a receiver operator characteristic curve describing theability of plasma hsa-miR-150-5p to predict cervical shortening at12-14⁺⁶ weeks gestation (AUC=0.86).

FIG. 20 shows a receiver operator characteristic curve describing thecombined ability of plasma hsa-miR-150-5p, hsa-miR-19b-3p,hsa-miR-185-5p and hsa-miR-374a-5p to predict cervical shortening at12-14⁺⁶ weeks gestation (AUC=0.87).

FIG. 21 shows a receiver operator characteristic curve describing thecombined ability of all nine plasma microRNAs to predict cervicalshortening at 12-14⁺⁶ weeks gestation (AUC=0.90).

DETAILED DESCRIPTION OF THE INVENTION

The present invention is based upon the surprising discovery of a groupof miRNA molecules which are present in the maternal circulation andwhose concentration in the circulation predicts subsequent cervicalshortening. For each of the miRNA molecules identified herein, theconcentration of miRNA in the maternal circulation is altered in womenwhose cervix subsequently shortens. Advantageously, expression levels oftheses miRNA can be measured from blood samples which can be obtainedfrom woman in the early stages of pregnancy (from gestation week 12onwards), thereby providing a minimally-invasive means for earlydetection/prediction of cervical shortening, which can lead to pretermlabour.

Therefore, the first aspect of the invention provides a method forpredicting risk of cervical shortening in a pregnant female subject,comprising determining the expression level of one or more of the miRNAmolecules identified in Table 1 or Table 2 extracted from a biologicalsample obtained from said subject and comparing to a control value,wherein a difference in the expression level of the one or more of themiRNA molecules compared to the control value indicates that the subjectis at high or low risk of cervical shortening.

If the miRNA molecule that is detected using the method according tothis aspect of the invention is a molecule whose over-expression isassociated with increased risk of cervical shortening (this includeseach of the miRNAs identified in Table 1), then an elevated expressionlevel of said miRNA in the patient's sample compared to the controlvalue is indicative of high risk of cervical shortening in said patient.

If the miRNA molecule that is detected using the method according tothis aspect of the invention is a molecule whose under-expression isassociated with increased risk of cervical shortening, then anexpression level of said miRNA in the patient's sample that is lowerthan the control value is indicative of high risk of cervical shorteningin said patient.

The direction of change of the difference in expression compared to thecontrol value (i.e. elevated or decreased expression) that is indicativeof high risk of cervical shortening for each of the miRNAs of theinvention is indicated in the final column of Tables 1 and 2.

For all of the miRNAs listed in Table 1, and all of the miRNAs listed inTable 2 except for hsa-miR-188-5p, an elevated expression level of themiRNA molecule compared to the control value indicates that the subjectis at high risk of cervical shortening.

For the miRNA hsa-miR-188-5p (Table 2) a decrease in the expressionlevel of the miRNA molecule compared to the control value indicates thatthe subject is at high risk of cervical shortening.

If, as a result of carrying out the method of the invention, the patientis identified as being at high risk of cervical shortening, then furtherdiagnostic testing or monitoring such as ultrasound screening ofcervical length could be offered. If the cervix is found to be short thepatient can be treated with therapeutic interventions.

Suitable therapeutic interventions include administering one or more of:oxytocin receptor antagonists, prostaglandin receptor antagonists,beta-adrenergic receptor agonists, nitrogen oxide donors, magnesiumsulphate, prostaglandin-synthase inhibitors, non-steroidalanti-inflammatory drugs (NSAIDs), small molecule and otheranti-inflammatory drugs, calcium channel blockers, progesterone,17-a-hydroxyprogesterone caproate, and progesterone analogues. Thepatient may additionally or alternatively be treated with surgicalintervention such as cervical cerclage.

No difference in the expression level of said miRNA molecule in thepatient's sample compared with the control value, or change in theexpression level of said miRNA molecule compared with the control valuein opposite direction to that which is indicative of risk of cervicalshortening for said miRNA, indicates that the subject is at low risk ofcervical shortening. If the subject is identified as being at low riskof cervical shortening then further diagnostic testing and/ortherapeutic or surgical interventions such as those described herein areunlikely to be required.

As used herein, the term “cervical shortening” (also referred to as“cervical ripening”) refers to change (i.e. reduction) in the length ofthe cervix that occurs during pregnancy. Cervical shortening to a lengthof around 25 mm or less is a cause of pregnancy loss and early pretermdelivery, and despite preventative treatment, about 50% of women whosecervix shortens will go on to delivery preterm.

The group of miRNA markers identified by the present inventors can alsobe used to determine risk of a pregnant subject suffering preterm labour(PTL).

As such, a second aspect of the invention provides a method forpredicting risk of PTL in a pregnant subject, comprising determining theexpression level of one or more miRNA molecules identified in Table 1 orTable 2 extracted from a biological sample obtained from said subjectand comparing to a control value, wherein a difference in the expressionlevel of the one or more of the miRNA molecules compared to the controlvalue indicates that the subject is at high or low risk of PTL.

If the miRNA molecule that is detected using the method according tothis aspect of the invention is a molecule whose over-expression isassociated with increased risk of PTL, then an expression level of saidmiRNA in the patient's sample that is elevated compared with the controlvalue is indicative of high risk of PTL in said patient.

If the miRNA molecule that is detected using the method according tothis aspect of the invention is a molecule whose under-expression isassociated with increased risk of PTL, then an expression level of saidmiRNA in the patient's sample that is lower than the control value isindicative of high risk of PTL in said patient.

If, as a result of carrying out the method of the invention, the patientis identified as being at high risk of PTL, then further diagnostictesting or monitoring can be carried out and/or the patient can betreated with therapeutic interventions, which aim to prevent a pretermbirth. Suitable therapeutic interventions include administering one ormore of: oxytocin receptor antagonists, prostaglandin receptorantagonists, beta-adrenergic receptor agonists, nitrogen oxide donors,magnesium sulphate, prostaglandin-synthase inhibitors, non-steroidalanti-inflammatory drugs (NSAIDs), small molecule and otheranti-inflammatory drugs, calcium channel blockers, progesterone,17-a-hydroxyprogesterone caproate, and progesterone analogues. Thepatient may additionally or alternatively be treated with surgicalintervention, such as cervical cerclage.

The direction of change of the difference in expression compared to thecontrol value that is indicative of high risk of PTL for each of themiRNAs of the invention is indicated in the final column of Tables 1 and2.

For all of the miRNAs listed in Table 1, and all of the miRNAs listed inTable 2 except for hsa-miR-188-5p, an elevated expression level of themiRNA molecule compared to the control value indicates that the subjectis at high risk of PTL.

For the miRNA hsa-miR-188-5p (Table 2) a decrease in the expressionlevel of the miRNA molecule compared to the control value indicates thatthe subject is at high risk of PTL.

No difference in the expression level of said miRNA molecule in thepatient's sample compared with the control value, or difference in theexpression level of said miRNA molecule compared with the control valuein opposite direction to that which is indicative of risk of PTL forsaid miRNA, indicates that the subject is at low risk of PTL. If, as aresult of carrying out the method of the invention, the subject isidentified as being at low risk of PTL then further diagnostic testingor monitoring and/or therapeutic interventions are unlikely to berequired.

The term “preterm labour (PTL)” refers to the condition where labourbegins three or more weeks before the full gestation period of about 40weeks (i.e. labour begins at 37 weeks of gestation or less). PTL canlead to a premature (or preterm) birth.

The term “high risk” refers to a level of risk of cervical shortening orPTL whereby further diagnostic testing, monitoring of the patient ortherapeutic intervention is appropriate. The term “low risk” refers to alevel of risk of cervical shortening or PTL whereby further diagnostictesting, monitoring of the patient or therapeutic or surgicalintervention is unlikely to be necessary.

As used herein, the term “therapeutic intervention” refers to treating apatient by administering one or more drugs. The term “surgicalintervention” refers to performing a surgical procedure on the patient.

The methods of the first and second aspects of the invention can beapplied to a general low risk obstetric population, in order to identifyrisk of cervical shortening and/or PTL in women who have no medicalhistory that would indicate that they are at risk of cervical shorteningand/or PTL, and who would otherwise not be placed under surveillance orreceive any therapeutic or surgical intervention to prevent cervicalshortening and/or PTL.

Alternatively, the methods of the invention can be applied to a highrisk obstetric population, comprising pregnant women who do have asignificant personal medical history including one or more of previousPTL, mid-trimester loss or cervical cone biopsy, which would indicatethat they are at risk of cervical shortening and/or PTL.

All women who demonstrate cervical shortening are offered some sort ofpreventative treatment (usually either cervical cerclage or drug therapysuch as progesterone), and so the same group of miRNA markers that havebeen identified by the present inventors are also useful for predictingthe need for therapeutic intervention. This is particularly useful inthe context of differentiating between pregnant subjects who have ahistory of previous PTL, mid-trimester loss or cervical cone biopsy andare in need of cervical ultrasound screening, cervical cerclage and/orprogesterone therapy, and those who have a background history that putsthem at risk of PTL but who do not require such treatment orintervention.

Identifying patients in high risk of preterm birth populations whosecervix will not go on to shorten enables them to be eliminated from highintensity surveillance of cervical length. This is advantageous from thepatient's perspective, because they are not subject to unnecessaryultrasound screening visits, and also from the perspective of publichealth service providers, as resources can be used in a more efficientand focused manner.

Therefore, the third aspect of the invention provides a method forcharacterising a pregnant subject having a history of previous PTL,mid-trimester loss or cervical cone biopsy as being in need of cervicalultrasound screening, and potentially therapeutic or surgicalintervention, comprising determining the expression level of one or moremiRNA molecules identified in Table 1 or Table 2 extracted from abiological sample obtained from said subject and comparing to a controlvalue, wherein a difference in the expression level compared with thecontrol value indicates that the subject is in need of cervicalultrasound screening, and potentially therapeutic or surgicalintervention.

If the miRNA molecule that is detected using the method according tothis aspect of the invention is a molecule whose over-expression isassociated with increased risk of cervical shortening and/or PTL, thenan expression level of said miRNA in the patient's sample that iselevated compared with the control value is indicative of need forcervical ultrasound screening, therapeutic and/or surgical intervention.

If the miRNA molecule that is detected using the method according tothis aspect of the invention is a molecule whose under-expression isassociated with increased risk of cervical shortening and/or PTL, thenan expression level of said miRNA in the patient's sample that is lowerthan the control value is indicative of need for cervical ultrasoundscreening, therapeutic and/or surgical intervention.

If, as a result of carrying out the method of the invention, the patientis identified as being in need of cervical ultrasound screening,therapeutic and/or surgical intervention then such screening and/ortherapy and/or surgery can be administered. Suitable therapeuticinterventions include administering one or more of: oxytocin receptorantagonists, prostaglandin receptor antagonists, beta-adrenergicreceptor agonists, nitrogen oxide donors, magnesium sulphate,prostaglandin-synthase inhibitors, non-steroidal anti-inflammatory drugs(NSAIDs), small molecule and other anti-inflammatory drugs, calciumchannel blockers, progesterone, 17-a-hydroxyprogesterone caproate, andprogesterone analogues. Suitable surgical intervention includes cervicalcerclage.

The direction of change of the difference in expression compared to thecontrol value that is indicative of high risk of cervical shorteningand/or PTL for each of the miRNAs of the invention is indicated in thefinal column of Tables 1 and 2.

For all of the miRNAs listed in Table 1, and all of the miRNAs listed inTable 2 except for hsa-miR-188-5p, an elevated expression level of themiRNA molecule compared to the control value indicates that the subjectis at high risk of cervical shortening and/or PTL.

For the miRNA hsa-miR-188-5p (Table 2) a decrease in the expressionlevel of the miRNA molecule compared to the control value indicates thatthe subject is at high risk of cervical shortening and/or PTL.

No difference in the expression level of said miRNA molecule in thepatient's sample compared with the control value, or a difference in theexpression level of said miRNA molecule compared with the control valuein opposite direction to that which is indicative of risk of cervicalshortening or PTL for said miRNA, indicates that the subject is not inneed of cervical ultrasound screening, therapeutic and/or surgicalintervention. In this case, further screening and/or therapy and/orsurgery are not required and on the basis of this result a clinician maydecide that the patient's pregnancy can proceed without any therapeuticor surgical intervention or monitoring of cervical length.

It will be apparent to the person skilled that the methods of theinvention disclosed herein can be used in conjunction with other methodsfor screening for PTL and determining cervical length that are wellknown in the art.

The terms “patient” and “subject” are used interchangeably herein andrefer to any female animal (e.g. mammal), including, but not limited to,humans, non-human primates, canines, felines, rodents and the like.Preferably, the subject or patient is a human female.

The terms “microRNA”, “miRNA” and “miR” are used interchangeably hereinand refer to small non-coding RNA molecules.

The methods of the invention described herein are carried out ex vivo.For the avoidance of doubt, the term “ex vivo” has its usual meaning inthe art, referring to methods that are carried out in or on a biologicalsample in an artificial environment outside the body of the patient fromwhom the biological sample has been obtained.

All references herein to a “biological sample” preferably refer to ablood sample. As used herein, the term “blood sample” includes wholeblood and blood components, including plasma and serum. In preferredembodiments, the one or more miRNA molecules are extracted from theplasma component of a whole blood sample or from the serum component ofa whole blood sample.

As used herein, “plasma” refers to the fluid portion of blood, excludingblood cells and platelets, but including dissolved proteins, glucose,clotting factors, electrolytes and hormones. As used herein, “serum”refers to blood plasma without clotting factors.

The skilled person will be familiar with standard phlebotomy techniqueswhich are suitable for obtaining a blood sample from a subject. Theskilled person will also be familiar with routine techniques forobtaining plasma and/or serum from a whole blood sample, e.g. usingcentrifugation.

In a preferred embodiment of each of the first, second and third aspectsof the invention the methods are carried out using biological samplesobtained at between 12 to 24 weeks gestation, preferably at between 12to 16 weeks gestation (also referred to herein as “time point A”),and/or at between 16 to 18 weeks gestation (also referred to herein as“time point B”), and/or at between 18 to 24 weeks gestation (alsoreferred to herein as “time point C”).

As the skilled person will readily understand, references to gestationalperiods used herein use the standard notation of “number of weeks⁺⁶”, toindicate a number of gestational weeks plus up to 6 days.

In a preferred embodiment of each of the first, second and third aspectsof the invention the expression level of a combination of two or more ofthe miRNA molecules identified in Table 1 or Table 2 or Table 3, andpreferably a combination of three or four of the miRNA moleculesidentified in Table 1 or Table 2 or Table 3 is determined. In aparticularly preferred embodiment the expression level of all nine ofthe miRNAs in Table 1 is determined. In such embodiments of the first,second and third aspects of the invention, the combined expression levelof the two, three or four or more miRNA molecules is compared to thecontrol value.

As used herein in relation to the first, second and third aspects of theinvention, the term “control value” refers to a baseline expressionlevel of the corresponding miRNA molecule(s) in a corresponding controlsample. The corresponding control sample may be obtained from a cohortof pregnant female subjects who reached full-term (>37 weeks gestation)with no cervical shortening.

If the expression level of two or more miRNA molecules is determined inthe methods of the invention, the corresponding control value is thecombined baseline expression level of the corresponding miRNAs in acontrol sample.

Preferably, for each of the methods of the invention, the cut-off valuefor determining whether the expression level of a given miRNA moleculeis “different” (elevated or reduced) compared with a control value is2-times the baseline expression level for the miRNA. Therefore if theexpression level of a given miRNA (e.g. hsa-let-7a-5p) is determined andthe expression value is found to be at least 2-fold greater than thebaseline expression level for hsa-let-7a-5p in a control sample, then itcan be concluded that hsa-let-7a-5p expression is elevated in thesubject's sample and a prediction of risk can be made, in accordancewith the methods of the first, second, third and fourth aspects of theinvention.

The term “expression level” is used broadly to include a genomicexpression profile, e.g. an expression profile of miRNAs. The expressionlevel of the one or more miRNA molecules in the patient's sample and/orthe control sample can be determined using any convenient means fordetermining a level of a nucleic acid sequence, e.g. quantitativenucleic acid hybridization of miRNA, labelled miRNA, and/or nucleic acidamplification techniques which are routinely use in the art and whichthe skilled person will be familiar with.

Preferred techniques for determining the miRNA expression level include:

-   -   Real-time PCR (RT-PCR)—this technique is suitable for large        scale/multiple analysis and so useful for screening large        populations;    -   Microarray—2D array on a solid substrate;    -   Next generation sequencing platforms (e.g. RNAseq)—the        advantages of next generation sequencing are that it is high        throughput, fast and has a low cost per base; and    -   In situ hybridisation.

The present inventors have identified the miRNAs listed in Table 1 andTable 2 as being useful in the context of the present invention. Inpreferred embodiments of each of the first, second, third or fourthaspects of the invention, the one or more miRNAs are selected from thegroup of miRNAs presented in Table 1. In particularly preferredembodiments the expression level of all nine of the miRNAs in Table 1 isdetermined.

TABLE 1 Direction of difference in expression miRNA Nucleotide sequenceAccession No. compared to control hsa-let-7a-5p ugagguaguagguuguauaguuMIMAT0000062 Increased (SEQ ID NO. 1) hsa-miR-374a-5puuauaauacaaccugauaagug MIMAT0000727 Increased (SEQ ID NO. 2)hsa-miR-15b-5p uagcagcacaucaugguuuaca MIMAT0000417 Increased(SEQ ID NO. 3) hsa-miR-19b-3p ugugcaaauccaugcaaaacuga MIMAT0000074Increased (SEQ ID NO. 4) hsa-miR-23a-3p aucacauugccagggauuuccMIMAT0000078 Increased (SEQ ID NO. 5) hsa-miR-93-5pcaaagugcuguucgugcagguag MIMAT0000093 Increased (SEQ ID NO. 6)hsa-miR-150-5p ucucccaacccuuguaccagug MIMAT0000451 Increased(SEQ ID NO. 7) hsa-miR-185-5p uggagagaaaggcaguuccuga MIMAT0000455Increased (SEQ ID NO. 8) hsa-miR-191-5p caacggaaucccaaaagcagcugMIMAT0000440 Increased (SEQ ID NO. 9)

TABLE 2 Direction of difference in expression miRNA Nucleotide sequenceAccession No. compared to control hsa-miR-106b-5p uaaagugcugacagugcagauMIMAT0000680 Increased (SEQ ID NO. 10) hsa-miR-22-3paagcugccaguugaagaacugu MIMAT0000077 Increased (SEQ ID NO. 11)hsa-miR-26b-5p uucaaguaauucaggauaggu MIMAT0000083 Increased(SEQ ID NO. 12) hsa-let-71-5p ugagguaguaguuugugcuguu MIMAT0000415Increased (SEQ ID NO. 13) hsa-miR-4454 ggauccgagucacggcacca MIMAT0018976Increased (SEQ ID NO. 14) hsa-miR-144-3p uacaguauagaugauguacuMIMAT0000436 Increased (SEQ ID NO. 15) hsa-miR-223-3pugucaguuugucaaauacccca MIMAT0000280 Increased (SEQ ID NO. 16)hsa-miR-92a-3p uauugcacuugucccggccugu MIMAT0000092 Increased(SEQ ID NO. 17) hsa-let-7b-5p ugagguaguagguugugugguu MIMAT0000063Increased (SEQ ID NO. 18) hsa-miR-188-5p caucccuugcaugguggagggMIMAT0000457 Decreased (SEQ ID NO. 19) hsa-miR-16-5puagcagcacguaaauauuggcg MIMAT0000069 Increased (SEQ ID NO. 20)hsa-let-7g-5p ugagguaguaguuuguacaguu MIMAT0000414 Increased(SEQ ID NO. 21) hsa-miR-148b-3p ucagugcaucacagaacuuugu MIMAT0000759Increased (SEQ ID NO. 22) hsa-miR-122-5p uggagugugacaaugguguuugMIMAT0000421 Increased (SEQ ID NO. 23)

Table 3 is a subset of the miRNAs listed in Table 2. In an embodiment ofthe first, second, third or fourth aspects of the invention, the one ormore miRNAs may be selected from the group of miRNAs presented in Table3.

TABLE 3 Direction of difference in expression miRNA Nucleotide sequenceAccession No. compared to control hsa-miR-106b-5p uaaagugcugacagugcagauMIMAT0000680 Increased (SEQ ID NO. 10) hsa-miR-22-3paagcugccaguugaagaacugu MIMAT0000077 Increased (SEQ ID NO. 11)hsa-miR-26b-5p uucaaguaauucaggauaggu MIMAT0000083 Increased(SEQ ID NO. 12) hsa-let-71-5p ugagguaguaguuugugcuguu MIMAT0000415Increased (SEQ ID NO. 13) hsa-miR-4454 ggauccgagucacggcacca MIMAT0018976Increased (SEQ ID NO. 14) hsa-miR-144-3p uacaguauagaugauguacuMIMAT0000436 Increased (SEQ ID NO. 15) hsa-miR-223-3pugucaguuugucaaauacccca MIMAT0000280 Increased (SEQ ID NO. 16)hsa-let-7b-5p ugagguaguagguugugugguu MIMAT0000063 Increased(SEQ ID NO. 18) hsa-miR-188-5p caucccuugcaugguggaggg MIMAT0000457Decreased (SEQ ID NO. 19) hsa-miR-16-5p uagcagcacguaaauauuggcgMIMAT0000069 Increased (SEQ ID NO. 20) hsa-miR-148b-3pucagugcaucacagaacuuugu MIMAT0000759 Increased (SEQ ID NO. 22)hsa-miR-122-5p Uggagugugacaaugguguuug MIMAT0000421 Increased(SEQ ID NO. 23)

For the avoidance of doubt, “hsa-” refers to Homo sapiens and is astandard abbreviation to differentiate the miRNAs from those of otherspecies. The suffixes “3p” and “5p” denote 3 prime or 5 prime,respectively. These suffixes are used to distinguish two miRNAsoriginating from opposite arms of the same pre-miRNA. “let-7” refers tothe lethal-7 gene, which is a miRNA precursor.

All miRNAs are identified herein using standard nomenclature. Sequenceinformation for each of the miRNAs listed in Tables 1 and 2 can be foundon the miRBase database maintained by Manchester University(www.mirbase.org).

The data shown in FIGS. 1-9 demonstrate the ability of each of the nineindividual miRNAs listed in Table 1 to predict cervical shortening. Thedata shown in FIGS. 10-19 demonstrate the utility of the same ninemiRNAs listed in Table 1 in predicting preterm birth.

These data are supported by a further study carried out by theinventors, wherein the expression level of the nine specific miRNAs ofTable 1 was determined in plasma from a second population of pregnantwomen at 12-14⁺⁶ weeks gestation (n=87). The data generated in thisfollow-up study, shown in Table 4 below, and in FIGS. 19-21, replicatethe initial findings of increased cell-free specific miRNA expression inplasma from women who exhibited subsequent cervical shortening. Table 4shows the expression of specific plasma miRNAs at 12-14⁺⁶ weeksgestation in women who went on to have cervical shortening (n=18)compared with women with no cervical shortening (n=69). Significantlyhigher expression of all nine microRNAs is observed in plasma from womenwho went on to have cervical shortening (cervical length <25 mm)compared with women with a normal cervical length.

TABLE 4 Area under receiver Mean fold Inter- operator change in quartilecharacteristic MicroRNA expression range P value curve* hsa-miR-93-5p3.1 0.8-3.9 0.0001 0.76 hsa-miR-191-5p 3.7 1.6-4.7 0.0001 0.79hsa-let-7a-5p 2.2 0.9-2.4 0.0054 0.72 hsa-miR-374a-5p 4.2 1.5-5.1<0.0001 0.82 hsa-miR-150-5p 5.8 2.7-7.6 <0.0001 0.86 hsa-miR-15b-5p 3.71.3-3.9 <0.0001 0.79 hsa-miR-185-5p 3.6 1.1-4.2 <0.0001 0.80hsa-miR-19b-3p 3.1 0.8-3.9 <0.0001 0.82 hsa-miR-23a-3p 5.1 1.5-6.7<0.0001 0.66 *Receiver operator characteristic curves were calculatedusing data from the original discovery population combined with thesecond validation cohort (n = 119).

The replication of the earlier findings in an independent population ofwomen supports the inventors' hypothesis that specific miRNAs may act asperipherally available biomarkers of future cervical shortening andsubsequent preterm birth. The inventors found that the combination ofdata from all nine microRNAs resulted in the strongest predictive power(see FIG. 21).

Since the miRNA markers listed in Table 1 and Table 2 are useful forpredicting cervical shortening, they can also be used to predict thetiming of the onset of labour at term, which is associated with cervicalshortening. Therefore, the miRNA markers listed in Table 1 and Table 2have utility for women who have reached at term, as well at pretermstages of pregnancy.

Therefore, a fourth aspect of the invention provides a method forpredicting the timing of the onset of labour in a pregnant subject whois at term (>37 weeks gestation), comprising determining the expressionlevel of one or more miRNA molecules identified in Table 1 or Table 2extracted from a biological sample obtained from said subject andcomparing to a control value, wherein a difference in the expressionlevel of the one or more of the miRNA molecules compared to the controlvalue indicates the timing of the onset of labour.

If the miRNA molecule that is detected using the method according tothis aspect of the invention is a molecule whose over-expression isassociated with cervical shortening, then an expression level of saidmiRNA in the patient's sample that is greater than the control value isindicative of onset of labour in said patient.

In a preferred embodiment of this aspect of the invention, theexpression level of a combination of two or more of the miRNA moleculesidentified in Table 1, Table 2 or Table 3, and preferably a combinationof three or four of the miRNA molecules identified in Table 1, Table 2or Table 3 is determined. In this embodiment, the combined expressionlevel of the two, three or four or more miRNA molecules is compared tothe control value.

In a preferred embodiment, the expression level of a combination of allnine of the miRNAs identified in Table 1 is determined.

As used herein in relation to the fourth aspect of the invention, theterm “control value” refers to the expression level of the correspondingmiRNA molecule(s) in a corresponding control sample obtained from acohort of pregnant female subjects who fail to go into labourspontaneously at 42 weeks gestation.

If the expression level of two or more miRNA molecules is determined inthe method of the invention, the corresponding control value is thecombined baseline expression level of the corresponding miRNAs in acontrol sample.

Preferably, as described above, the cut-off value for determiningwhether the expression level of a given miRNA molecule is “different”(elevated or reduced) compared with a control value is 3-times thebaseline expression level for the miRNA.

In other aspects of the invention, the miRNA molecules identified inTables 1 and/or 2 and/or 3 can be used to determine the likely responseof a patient to agents used for induction of labour at any gestationalage. Such agents include, for example, prostaglandins and oxytocin.

Furthermore, the miRNA molecules identified in Tables 1 and/or 2 and/or3 can also be used to determine the risk of caesarean section associatedwith induction of labour, in a patient at any gestational age.

The present inventors have identified that differences in expressionlevels of miRNAs compared to a control value, which can predict pretermcervical shortening, are also predictive of easy induction of labour atterm. Females who are going to go overdue (i.e. delivery at >40 weeksgestation) will have a longer cervix (and the associated levels of miRNAmarkers disclosed herein) and are likely to have a higher risk ofinduction failure and a higher risk of need for Caesarean section.

The fifth aspect of the invention provides a support material, which isa solid substrate, such as a biochip, comprising one or more probesspecific for one or more of the miRNA molecules in Table 1 or Table 2attached thereto or immobilised thereon. In a preferred embodiment, thesupport material comprises probes specific for each of the nine miRNAmolecules identified in Table 1.

As used herein, the term “probe” refers to an oligonucleotide capable ofbinding to a target nucleic acid (i.e. a miRNA molecule) ofcomplimentary sequence. Probes may bind to targets lacking completecomplementarity with the probe sequence, depending upon the stringencyof the hybridisation conditions. Probes may be directly labelled orindirectly labelled, such as with biotin to which a streptavidin complexmay later bind.

The probes may be capable of hybridising to a target miRNA sequenceunder stringent hybridisation conditions. The probes may be attached atspatially defined locations on the substrate. The solid substrate may bea material that may be modified to contain discrete individual sitesappropriate for the attachment or association of the probes and isamenable to at least one detection method. Examples of suitablesubstrates include glass and modified or functionalised glass, plastics,polysaccharides, nylon or nitrocellulose, resins, silica or silica-basedmaterials, carbon and metals. The substrate may allow optical detectionwithout appreciably fluorescing.

The substrate may be planar, although other configurations of substratesmay be used as well. For example, probes may be positioned on the insidesurface of a tube.

The support material and the probe may be derivatized with a chemicalfunctional group, such that the probe may be attached using thefunctional group directly or indirectly using a linker. Alternatively,the probe may be attached to the solid support non-covalently, forexample using biotinylated oligonucleotides. Alternatively the probe maybe synthesised on the surface of the solid support using techniques suchas photopolymerization and photolithography.

Preferably, the support material comprises oligonucleotide sequencesspecific to each of the one or more miRNA molecules. The supportmaterial can be used in a method according to any of the first, second,third or fourth aspects of the invention.

The present invention also provides kits for predicting risk of cervicalshortening and/or preterm labour (PTL) in a pregnant female subject,comprising one or more probes specific for one or more of the miRNAmolecules in Table 1 or Table 2. In addition, the kit may comprise anyor all of the following: assay reagents, buffers, probes and/or primers,sterile saline or another pharmaceutically-acceptable emulsion andsuspension base. In addition, kits may include instructions for use forthe practice of the methods described herein.

A kit according to the invention may be used to carry out any of themethods described herein.

The invention will be further described with reference to the followingnon-limiting example.

EXAMPLE

Materials and Methods

Sample Collection and Study Design:

Following ethical approval, whole blood samples were collected frompregnant women attending the dedicated prematurity surveillance clinicsat St. Mary's and Queen Charlotte's and Chelsea Hospitals, London. Bloodwas taken at three different time-points during pregnancy; 12+0-14+6(time point A), 15+0-17+6 (time point B) and 19+0-21+6 (time point C),and stored. Approximately 3 ml of whole blood was obtained. The sampleswere placed on ice immediately and centrifuged at 1300 g for 10 minutesat 4° C. within 30 min of collection. Isolated plasma was stored in 1000μl aliquots in natural RNAase free microtubes at −80° C. Samplesdemonstrating macroscopic haemolysis were discarded. Following delivery,samples were allocated to phenotypic cohorts depending on whether womenwent on to exhibit either cervical shortening and preterm delivery(n=25), cervical shortening and term delivery (n=31) or no cervicalshortening with term delivery (n=48). (Preterm delivery not preceded bycervical shortening is very rare in this population).

RNA Extraction:

Plasma aliquots were thawed on ice. In order to minimise cellular andplatelet contamination, samples were further spun at 800 g for 10 min at4° C. The upper 750 ul was removed for onward processing and theremaining plasma discarded. RNA was extracted using the ‘Plasma/SerumCirculating and Exosomal RNA Purification Mini Kit (Slurry Format)’(Norgen Biotek, Ontario, Canada) according to the manufacturer'sinstructions. In addition, 5000 attomoles synthetic cel-254 (sequenceUGCAAAUCUUUCGCGACUGUAGG (SEQ ID NO. 24), Integrated DNA TechnologiesBVBA, Leuven, Belgium) was spiked-in to the plasma following theaddition of lysis and denaturing buffers to allow downstreamnormalisation of any technical variation to the extraction process.Eluted RNA was further purified and concentrated using Amicon Ultra YM-3columns (Merck Millipore, Darmstadt, Germany).

nCounter™ Profiling:

RNA was sent externally for profiling using the nCounter™ plasma miRNAcassette (Nanostring, Seattle, USA). This technique permits target miRNAexpression levels to be directly assessed, without enzymatic reactions,via two sequence-specific probes¹¹. The individual mRNA is captured withone miRNA target sequence-specific capture probe that is then used in apost-hybridization affinity purification procedure. The second miRNAtarget specific-sequence and fluorescent-tagged, coded probe is thenused in the detection with the 3-component complex separated on asurface via an applied electric field followed by microscopy imaging.

Reverse Transcription and Real Time Polymerase Chain Reaction:

RNA was reverse transcribed to cDNA following the addition of 0.625 μlsynthetic miRNA UniSp6 (10⁸ copies/μl) (Exiqon, Vedbaek, Denmark) toallow downstream normalisation of any technical variation to thereaction. Real time polymerase chain reaction was performed using custom‘pick and mix’ panels containing LNA™ primers, according to themanufacturer's instructions (Exiqon, Vedbaek, Denmark).

Data Analysis:

nCounter™

Background signal was defined as two standard deviations above the meanof negative control probes and subtracted from the raw miRNA moleculecounts. Expression counts were normalised to the mean expression of thetop 100 expressed miRNAs. MiRNA probes without expression abovebackground in more than half of the samples from any clinical group wereremoved from further analysis. Samples with very high expression ofplatelet derived miRNAs hsa-miR-16 and hsa-miR-25 and hsa-miR-93 wereremoved from the analysis (n=2). Expression was compared betweenclinical groups using nSolver v2.0 software (Nanostring, Seattle, USA)and those miRNAs found to be differentially expressed with a falsediscovery rate <0.05 were considered to be discriminatory.

RT-PCR

Cycle threshold (Ct) values for each miRNA were calculated using steponev2.3 software (Life Technologies Ltd, Paisley, UK). Ct values weremedian normalised firstly to an inter-plate calibrator and then to theextraction and reverse transcription spiked-in controls. Distributionswere assessed for normality using the D'Agostino and Pearson omnibustest and clinical groups were compared using either Student's unpaired tor Mann-Whitney test as appropriate; a p value <0.05 was consideredsignificant. Fold change was calculated using 2^(−DG) where DG=mean Ctexperimental group−mean Ct normal group.

REFERENCES

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The invention claimed is:
 1. A method for reducing the risk of cervicalshortening or preterm labor (PTL) comprising: determining an elevatedexpression level of an miRNA molecule having SEQ ID NO:7 extracted froma biological sample obtained from a pregnant female subject as comparedto a control value; and administering to the subject one or more ofa-cervical ultrasound screening, therapeutic intervention, and surgicalintervention.
 2. The method according to claim 1, wherein thetherapeutic intervention is selected from one or more of oxytocinreceptor antagonists, prostaglandin receptor antagonists,beta-adrenergic receptor agonists, nitrogen oxide donors, magnesiumsulphate, prostaglandin-synthase inhibitors, non-steroidalanti-inflammatory drugs (NSAIDs), small molecule and otheranti-inflammatory drugs, calcium channel blockers, progesterone,17-a-hydroxyprogesterone caproate, and progesterone analogues.
 3. Themethod according to claim 1, wherein the expression level of acombination of SEQ ID NO:7 and one or more miRNA molecules selected fromSEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ IDNO:6, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ IDNO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ IDNO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ IDNO:22, and SEQ ID NO:23 is determined, and wherein the combinedexpression level of the two or more miRNA molecules is compared to thecontrol value.
 4. The method according to claim 3, wherein theexpression level of a combination of SEQ ID NO:7 and two, three or fourof the miRNA molecules selected from SEQ ID NO:1, SEQ ID NO:2, SEQ IDNO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:9,SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14,SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19,SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, and SEQ ID NO:23 isdetermined, and wherein the combined expression level of SEQ ID NO:7 andthe two, three or four miRNA molecules is compared to the control value.5. The method according to claim 1, wherein the method is carried out atbetween 12 to 24 weeks gestation.
 6. The method according to claim 5,wherein the method is carried out at between 12 to 16 weeks gestation,and/or at between 16 to 18 weeks gestation, and/or at between 18 to 24weeks gestation.
 7. A method for inducing labour in a pregnant subjectwho is at or more than 37 weeks gestation, comprising determining anelevated expression level of an miRNA molecule having SEQ ID NO:7extracted from a biological sample obtained from said subject ascompared to a control value and administering to the subject an agentused for induction of labour.
 8. The method according to claim 1 or 7,wherein the biological sample is a whole blood sample.
 9. The methodaccording to claim 8, wherein the miRNA molecule is extracted fromeither the serum or plasma component of the whole blood sample.
 10. Themethod according to claim 1 or 7, wherein the expression level of allnine of the miRNA molecules having SEQ ID NOs:1-9 are determined, andwherein the combined expression level of the nine miRNA molecules iscompared to the control value.
 11. The method according to claim 7,wherein the control value is the expression level of the correspondingmiRNA molecule in a corresponding control sample obtained from a cohortof pregnant female subjects who fail to go into labour spontaneously by42 weeks gestation.
 12. The method according to claim 1, wherein theexpression level of the miRNA molecule is determined using one or moreof the testing methods selected from the group consisting of nucleicacid hybridisation, nucleic acid amplification, real-time PCR,microarray, Next generation sequencing platforms, and in situhybridisation.